storage options for MacBook Air

I also use the AIFF format. And iTunes.

So the answer depends on the number of albums/songs in your library and if you plan to add to it.

I assumed that the external drive was used because you were running out of disk space on the MB Air. Which, as your library grows, is gonna happen.

For example, my Rollings Stones "Let It Bleed" CD to AIFF rip is 455 Megabytes. Not sure how much overhead Mac OS (or OSX) uses on that MB Air. But if an album runs 450 Megabytes per CD you could calculate how much of your library it could hold. 

If you like iTunes (and I do though I use Roon for playback but hear no difference in SQ from iTunes) then maybe consider a MacMini to run iTunes and output to the Ultra Fi. You control the Mini iTunes from the MB Air using Screen Share. That existing external drive could be connected to the Mini. 

hgeifman,
The MB Pro you had probably did not have a SSD drive which I'm guessing is why the retailer recommended the external LaCie hard drive. I've read that it's always good to keep music on an external drive.
I've also read that SSD makes a noticeable improvement over standard hard drive and my MB Air comes with built in SSD which makes my decision difficult.

dbtom2
My library will fit in the MB Air at this point, but you're right 250 GB will run out when my library grows. What Mac are you using?
I control itunes using the remote app and it works very well, no need for two different computers.

I listen to music on a (mostly headless) MacMini. The music is managed by iTunes. I've got almost 3/4 TB on a 2TB WD drive connected via firewire to the Mini.  The Mini USB out to an LH Labs DAC to HiFi.  This is my Roon core. 

I rip and control the MacMini from an iMac which is a Roon remote. The iMac has an Oppo HA-2 DAC/headphone amp for local listening

Both are wired via ethernet and I use Apple's Screen Sharing to manage the Mac, add music files etc.  

Your MB Air is a sweet portable device, an excellent remote control to the hifi stereo but capable of playback to personal listening too. 

Scar972, It can make a difference if your external (mechanical) storage is acoustically noisy.  Other than that your DAC has asynchronous (I believe) input, meaning that timing of the computer and DAC are separated.  What you send to DAC is data - not the music (you can use computer at the same time).  Music is recreated in the DAC by added timing (separate clock for D/A conversion).  I would not transfer files to SSD drive for two reasons.  First is better flexibility of external storage and the second is the fact that it can make your SSD last longer.  Your SSD has limited number of writes for each sector.  In order to extend it drive constantly reshuffles sectors to minimize the use of each sector.  The more free space you have the more years it will serve you.  Don't forget to make backups.  I make two backups to prevent situation when something bad happens during backup destroying both disks.  In addition my second backup, that I keep at work, gives me protection from fire, theft etc. 

Hello Scar972 - I have a MacBook Air and just moved to an Aries Mini for playing ripped files and streaming Tidal, Spotify and internet radio.  My music files are ALAC in iTunes and are on an external hard drive (plus backups).  Space being limited on the SSD of the MBA, I went external.  I could not tell a difference sound wise.  It should be easy to do the A/B comparison and decide for yourself.  I will say, if prices for solid state come down, I'd prefer to use solid state for storage over a mechanical hard drive.  Just seems the better tech for quickly transmitting data...whether or not it improves sound.  

Back to the MBA...I was also using BitPerfect ($10 from the App Store) to run things.  I highly recommend it for improved SQ over "native" iTunes if you stay with the MBA.  Also, if you go to an external hard drive for storage you can experiment with other formats besides AIFF...ALAC and WAV, at the least since space won't be an issue.

FWIW, the Aries Mini reads all my iTunes/ALAC files no problem.  I still use the MBA into a Schiit Asgard 2 via Dragonfly for headphone listening late at night.  

Hope that's helpful.